Process of making anhydrous sulfites and bisulfites.



' the product is packed with reasonable care. o

U TED srATEs PATENT orrron.

EMERSON H. STRICKLER, OE WHITE PLAINS, NEW YORK, ASSIGNOR TO GENERAL CHEMICAL COMPANY, OF NEW YORK, N; Y., A CORPORATION OF NEW YORK.

\ PROCESS OF MAKING ANHYDROUS SULFITES AND BISULFIT-ES.

No Drawing.

Specification of Letters Patent.

My Patented Apr. 16,1912.

Application filed January 4, 1908. Serial N 0. 409,278.

To all whom it may concern.

Be it known that I, EMERSON H. S'rRIoK- LER, a citizen of the United States, resident of White Plains, Westchester count-y, State of New York, have invented certain new and useful Improvements in Processes of Making Anhydrous Sulfites and Bisulfites,

of which the following is a specification.

My invention relates to a new process for making sulfites, and particularlyanhydrous sodium bisulfite, or anhydrous sodium sulfite, and has for its chief advantages alow cost of operation, and the fact that-there is little or no danger of the formation of sulfates byoxidation.

In making anhydrous bisulfite of soda (NaHSO according to my invention, I

In practice, more water is present than indicated by the equation, and a portion of the sodium bisulfite (NaHSO becomes dissolved in the excess water. The undissolved portion of the bisulfite is the real product ,which is separated from the solu-' tion in any suitable way,=as by settling or treatment in a centrifugabmachine. After drying, this product is in marketable condition. .It is commercially pure, containing but small amountsof Na SO and practically no sodium'sulfate '(Na SO nor is any materlal amount of sulfate formed by oxidation in the course of time, aslong as The supernatantor mother liquor con- 6 taining NaHSO in solution, may be neutralized xwit-h sodium carbonate, according to the following equation: L

2NaHSO +Na CO i v j QNa SO -I-CO kH O. I This sodium 'sulfite solution is then rep and the turned to the first stage of the process, so v as'to complete the cycle.

In practice I have found that 300 grams anhydrous sodium carbonate added to each 1000 grams of mother liquor are usually suflicient not only to neutralize the therein contained sodlum blsulfite, but also to pro duce a suspension suitable" for use in this,

my new process. I have also found, in

practice, that a temperature of substantially 120 F ahrenheitis usually a suitable temperature at which to operate.

The neutralization of the mother liquor (sodium bisulfite) by sodium carbonate, the formation of the suspension by the addition of sodium carbonate to the neutralized liquor and the treatment with sulfur dioxid canall be done in the same" tank, which should be provided with a mechanical agitator, means for introducing the S0 gas into the body of the suspension and means for discharging the resulting solid sodium bisulfite and the supernatant liquor; Or, if preferred, separate tanks may be used for the several steps of the process, or the process may be carried out in one or more towers.

When it is desired to make neutral anhy drous sodium sulfite (Na SO instead of anhydroussodium bisulfite (NaHSO the treatment differs from that described above [only by the fact that the supply of S0 is discontinued as soon as CO ceases to be dlsengaged. In this case the reaction may perhaps be represented by the following equation Instead of employing a solution of sodium sulfite having sodium carbonate suspended therein, I may use a solution of sodium carbonate in .which an excess of sodium carbonatc is suspended. The production of sodium bisulfite in that case might perhaps be represented the following equation:

production of sodium sulfite as followsr.

Again, I may employ a solution of sodium bisulfite having sodlum carbonate suspended therein, and produce from it anhydrous sodium bisulfite in the same manner, that is,

1 cases being a vehicle, the aflinity of which v lXlaHSO Will be'obtained';

' pended in a-suitable vehicl. g the art of manu-' "40 by u; introduction 'of sulfur djo'xid, 'dic ted by the equation: I

, 6NaHSO ,+2CQ,I Or, using less S0, toproduce Na sO we have 2NaHSOQ+2Na,CO ,-FSO,

' 1 zal igl so sz o g-r1 0. When sodium bisulfite is added to sodium carbonate,.it'is atonce converted into sodium i sulfite' so that, strictly speaking, at no time is 1 sodium carbonate suspended in sodium 'It will be seenthat I introduce $0 into a vehicle in which Naj CO is suspended, said vehicle in the cases described being either a solution of Na SO or ofNa CO and in all =for sulfur dioxid is not greater than that of sodium carbonate. Of course, I might use as an equivalent a mixture of two of these solutionor all three',but in any event, the solution or mixture of solutions should containLNa CO in suspension. If the admission of SQ is stopped when'CO ceases to be disengaged, the procss will produce anhydrous Na' SO if the supply of S0 -'is continued beyond this point, anhydrous I claim as my invention I 1. The improvement in the art of manufacturing an anhydrdus sulfite salt of sodium which consists in-bringingftogether sulfur dioxid, and sodium carbonate sus 1 2. The improvement m1 facturing an anhydrous .sulfite' salt of sodium which consists in bringing together subscribed my name, in the presence of two sulf-ur-diozgid, and sodium carbdnate suspended in aliquid vehicle, theafiinityof which for said'sul-fur dioxidis not greater than that of. sodiuin carbonatez' 3. The improvement in the art of manu;

facturing an 'anhydnous fsulfite salt of sodiumrwhich consists in bringing together sulfur dioxid,.and sodium carbonate suspended in a sodium salt; solution.

" 4. The improvement in the art of manufacturing an -anhydrous sulfite" salt of sodium which consists in bringing together sulfur} dioxid, and sodium carbonate suspended in a solution of sodium 'sulfite.

5. The improvement in the art of manu-' facturing an anhydrous sulfite salt of pended ina saturated sodium salt solution.

7. The improvement in the art of manufacturing anhydrous 'bisulfite, of sodium which consists in bringing together sulfur af'solution (if sodium sulfite.- vI-n testimony whereof I'have hereunto subscribing witnesses, this-31st'day of Dece nber, 1907.

V EMERSON H. STRIGKLER. I Witnesses: i J om; LO'T'KA,

Join: A. KEHLENBEcK.

jnd sodium carbonate suspended in 

